The following are reasons why contacting departed relatives through a medium or an Ouija board is detrimental:
Most mediums do not have the high level sixth sense ability (ESP) nor the spiritual level to discern the true identity of the spirit they are speaking to. In almost all cases, instead of our ancestors or our loved ones coming through, it is a ghost (demons, devils, negative energies etc.) who tries to communicate with us. These ghosts (demons, devils, negative energies etc.) can have our departed ancestors under their control, sometimes extracting personal information from them to fool us into thinking that we are indeed talking to our ancestors. This happens even if the ancestors do not want to give information to the ghosts (demons, devils, negative energies etc.). Ghosts (demons, devils, negative energies etc.) also have the ability to invade the mind of the ancestor and extract information from the ancestor. Sometimes the ghosts (demons, devils, negative energies etc.) purposely let the ancestors come through but force them to give wrong information to their descendants, thus leading the surviving relatives astray.
In almost all cases, mediums who are at lower spiritual levels are possessed by ghosts (demons, devils, negative energies etc.) without having the slightest inkling. Also most mediums do this for money and/or fame. Ghosts (demons, devils, negative energies etc.) use this desire in the medium to enhance their control over them. (Refer to: Who are more likely to fall prey to an attack by ghosts?) They sometimes enhance the ability of the medium to exert a wider and deeper influence. The medium interprets this improved ability as a sign of their personal progress, but this is far from the truth. Finally, ghosts (demons, devils, negative energies etc.) mislead people through the medium.
On the other hand mediums who have higher spiritual strength generally have a few ghosts (demons, devils, negative energies etc.) under their control. They use these ghosts (demons, devils, negative energies etc.) to get information about the people coming to them and who are in need of contacting their departed loved ones.
Sometimes we hear about "ghost whisperers" helping our ancestors to cross over. A ghost whisperer is another word for a medium who can communicate with the spirits of the dead. However, unless a ghost whisperer is above the 70% spiritual level (i.e. at Sainthood level), it is nearly impossible to help any subtle-body cross over to the higher positive regions from an Earthbound existence.
Trying to contact departed relatives only increases their feeling of attachment for us and vice versa. The departed ancestors can perceive the pain and mourning of their surviving relatives and are drawn back to the Earth region (Bhūlok). This creates obstacles in the subtle-body’s ability to move on and progress in the afterlife.
Only a person who is a Saint (i.e. above the spiritual level of 70%), can actually decipher information accurately from the spiritual realm about one's departed ancestors. They are able to discern whether contact is being made with the concerned ancestor or if a ghost (demons, devils, negative energies etc.) is masquerading as an ancestor. At present, there are less than 10,000 of these evolved people living on Earth and they generally never indulge in helping people talk to their dead relatives.
There is only a 10% chance of getting in touch with one’s departed ancestors by using an Ouija board. However the flip side is that there is also a 90% chance of a ghost (demons, devils, negative energies etc.) coming through masquerading as an ancestor. What is more damaging is that the ghost (demons, devils, negative energies etc.) can use the medium of the Ouija board itself to possess the person involved.
Losing a loved one can be a traumatic experience and one may have the desire to contact them to see if they are doing well. However the best service we can offer to our departed relatives is to make every effort to let them go. This is so that they can continue with their onward journey in the afterlife. Likewise, the best way to honour them and show our love for them is to let them go. Communicating with the dead has absolutely no spiritual value and will only create a loss to both the ancestor and to the descendant. It is important and beneficial to channel the sorrow of losing a loved one into doing spiritual practice and chanting the spiritual protection chant of Shrī Gurudev Datta. This will not only help alleviate the pain that one feels but also substantially assist the departed loved ones in their afterlife.